Wash your pears under cold running water, then pat them dry. Peel each pear and cut them in half lengthwise.

Scoop out the core and seeds, then roughly chop the pear flesh into 1 to 2-inch chunks.

Place the chopped pears into the large heavy pot and sprinkle the granulated sugar over the pears, stirring well to coat.

In a small bowl, combine the cinnamon, nutmeg, cloves, and salt. Add this spice mixture and lemon juice to the pot and stir to combine.

Set the burner to medium heat and bring the mixture to a gentle simmer, stirring occasionally.

After about 30 to 40 minutes of simmering, use a potato masher to break down the softened pear pieces into smaller bits.

Reduce the heat to low and let the butter bubble gently for 1 to 1.5 hours, stirring every 10 to 15 minutes.

After about 1.5 hours total cooking time, test the thickness by dropping a spoonful onto a cold plate.

For a completely smooth texture, use an immersion blender to puree the mixture directly in the pot.

Remove the pot from heat and stir in the vanilla extract if using. Adjust the flavor with more cinnamon or lemon juice if needed.

Let the butter cool for 5 to 10 minutes before transferring to jars.